Multimedia, Multipoint Communications.

This research project focused on two parallel, complementary research activities designed to address potential problems arising in the transmission of multimedia traffic to multiple parties over both nigh-speed wired and lower speed wireless communication networks of the future. The first addressed appropriate flowcongestion control in this multicast environment, and specifically the design of algorithms to control the flow of traffic between a source and multiple receivers, either fixed or mobile, located at possibly different distances from the source, so that the receivers can each handle the traffic flow, and yet provide as high a throughput as possible with queueing delays constrained to acceptable values. The second activity addressed the efficient transmission of digital, standards-based video MPEG-1MPEG-2 in this networking environment. To mitigate the highly variable nature of network conditions in terms of available bandwidth and delay, we investigated algorithms that combined rate shaping on-the-fly modification of the video bit rate and flow control to maximize the received video quality. To ensure that the video traffic is a fair and equitable user of the network, we used TCP flow control but no error control, so that video competes fairly for resources with traditional types of traffic which are predominantly TCP-based.